Field of the Invention
The invention relates to a circuit board structure and a manufacturing method thereof. More particularly, the invention relates to a circuit board structure having a cavity and a manufacturing method thereof.
Description of Related Art
Generally, to manufacture a circuit board structure having a cavity, it is necessary to fabricate an alignment copper layer on a core layer of an inner circuit layer. The purpose thereof is that during a subsequent process of forming the cavity by performing laser ablation on the circuit structure, the alignment copper layer serves not only as a laser resisting layer for preventing excessive ablation of the circuit structure, but also as a laser alignment pattern that facilitates the laser ablation process. However, since the alignment copper layer is directly formed on the core layer of the inner circuit layer, the circuit layout of the core layer is limited, thus reducing layout flexibility of the core layer.